Vane pump with one or more less restricted vanes

ABSTRACT

A vane pump that employs one or more less restricted vanes (or looser vanes) within its rotor is described herein. The less restricted vane(s) are configured to radially move outwardly before the remaining vanes during startup. In one case, for example, at least one vane has a different thickness (e.g., thinner) as compared to the thickness of the remaining vanes. In another case, at least one slot has a different width (e.g., wider) as compared to the width of the other slots. The less restricted vane facilitates a cold start in highly viscous oil by allowing easier radial displacement and thus earlier initial build-up of pressure in the pump. The pump may be used with an engine or transmission.

CROSS REFERENCE TO RELATED APPLICATION

This patent application claims priority to provisional patent application 62/432,194 filed on Dec. 9, 2016, and is incorporated by reference herein in its entirety.

BACKGROUND Field

The present disclosure is generally related to a variable displacement vane pump for providing pressurized fluid to a system. The vane pump has at least one vane that is less restricted and is configured to move within its slot before other vanes, for example, at cold start.

Description of Related Art

Vane pumps are known for use for pumping fluids or lubricants, such as oil, to internal combustion engines. The vanes are mounted to a rotor and engage the inner surface of a pressure chamber to generate a pressure differential to pump the fluid. Some vane pumps include a small spring in each vane slot, which increases cost and manufacturing complexity. It is also known to feed some of the pressurized fluid to the slots to bias the vanes using the pressure, thus avoiding the need for numerous small springs.

However, at startup of a pump where pressure is used to bias the vanes, the vanes are typically pushed inwardly towards the drive axis into their respective slots in the rotor by the pressure chamber, as there is no internal pressure to push the vanes radially out against the cam. During a normal pump start in room temperature oil (or warmer), the vanes are more easily displaced due to the centrifugal force. At colder oil temperatures, however, the viscosity of the oil increases. The thicker oil makes it more difficult for the vanes to move radially when the centrifugal force is applied, and thus the generation of pressure is delayed until the speed is increased sufficiently to generate enough centrifugal force to overcome the thick oil.

SUMMARY

It is an aspect of this disclosure to provide a vane pump having an inlet for receiving fluid from a source, and an outlet for delivering pressurized fluid to a system therefrom. A pressure chamber cam is also provided in the pump and has an internal space defined by an inside surface and communicated to the inlet and outlet. A rotor is rotatably received within the internal space of the pressure chamber cam and has a plurality of radial slots and a plurality of vanes received and movable within respective radial slots radially towards the inside surface of the pressure chamber cam. A drive shaft of the pump is connected to the rotor for rotating the rotor to cause the vanes to draw lubricant in from the inlet and pressurize the lubricant for expelling out through the outlet. The rotor has the radial slots thereof communicated to the pressurized fluid to bias the vanes radially outward therefrom using the fluid pressure. For at least one of the plurality of vanes, a distance between an outer face of the at least one vane and an inner face of its respective slot is greater than distances between outer faces of the remaining vanes and inner faces of their respective slots to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.

Another aspect of this disclosure includes a system having the above-noted vane pump along with an engine or transmission.

Other aspects, features, and advantages of the present disclosure will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a case with a vane pump in accordance with an embodiment of the present disclosure, assembled in the case.

FIG. 2 is a sectional view of the vane pump of FIG. 1 taken along line 2-2.

FIG. 3 is a top isometric view of parts of the vane pump in the case of FIG. 1 in accordance with an embodiment.

FIG. 4 is a sectional view of the vane pump as shown in FIG. 3 taken along line 4-4.

FIG. 5 is a bottom isometric view of the parts of the vane pump in accordance with an embodiment.

FIGS. 6A and 6B are a bottom isometric view and a bottom view, respectively, of a cam, rotor, and cover plate of the vane pump of FIGS. 3-5.

FIG. 7A is an isometric view of a bottom of the cover plate in the vane pump as shown in FIG. 3.

FIGS. 7B and 7C are isometric views of a top and a bottom, respectively, of the pressure plate in the vane pump of FIG. 3.

FIGS. 8A and 8B are detailed isometric and top views, respectively, of the vanes in the slots of the rotor in accordance with one embodiment of the present disclosure.

FIG. 9 is detailed view of the vanes in the slots of the rotor in accordance with another embodiment of the present disclosure.

FIG. 10 is a schematic diagram of a system in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Generally, this disclosure relates to providing at least one less restricted vane (or looser vane) in a rotor of a vane pump. In one embodiment, this disclosure is directed to a vane pump having (at least) one thinner/narrower vane (in thickness or width) such that it is less restricted within its slot—relative to the other vanes—for easier displacement in its respective slot of the rotor. In another embodiment, the slot of the rotor is wider to allow the vane to move more loosely in its slot as compared to the movement of other vanes within their respective slots. The less restricted vane facilitates a cold start in highly viscous oil by allowing easier radial displacement and thus earlier initial build-up of pressure in the pump.

The less restricted vane concepts as disclosed herein may be implemented in different types of vane pumps. For example, in one embodiment, the pump may be a fixed displacement pump wherein the relationship between the rotor and pressure chamber is fixed. Such a fixed displacement pump may be configured to provide a maximum flow rate and pressure based on a peak demand of the system. In another embodiment, the pump may be a variable vane pump wherein the relationship between the rotor and pressure chamber varies, such as by using a cam ring. The variable vane pump may have a multi-chamber design.

Pump 10 has a housing or case associated therewith. In one embodiment, the pump 10 has its own separate housing 12, case, or casing (which are used interchangeably herethroughout) for enclosing its parts as shown in FIGS. 1-2. That is, the parts of the pump 10 are contained within a structure, such that the housing 12 forms a self-contained device around working and/or moving parts of the pump, and thus the pump 10 may be inserted, connected, and/or secured to another part via housing 12. FIG. 1 is an isometric view of a case, such as a transmission case, with a pump assembly 10 (or pump) assembled therein in accordance with an embodiment of the present disclosure. In another embodiment, the parts of the pump 10 may be assembled and contained within an opening or main chamber 55 (shown in FIG. 2) formed within another case, housing, or part (e.g., of a transmission case); thus, the opening or chamber 55 forms the volume within pump housing 12. One or more O-rings may be provided to secure the pump 10 within the housing 12. The housing or chamber 55 may have an inner bore, for example, for receiving a pressure chamber cam ring 20 (also referred to as simply a cam or a ring), a rotor 34 (or impeller), and a drive shaft 18 of the pump assembly 10, as is known in the art and described in some detail later. In other types of pump devices, the cam or cam ring 20 may sometimes be referred to as a slide or slide ring that is capable of sliding or moving, whereas as in the pump described herein, the cam 20 is located or secured in its position using pins 32.

The pump has an inlet 13 and an outlet 15, which are formed via openings 17 and 19 (respectively) through wall(s) in the housing 12, as shown in FIG. 2. The inlet 13 and outlet 15 of the housing 12 may be provided at an angle relative to each other, in one embodiment. In an embodiment, the inlet 13 and outlet 15 may be disposed such that fluid or lubricant is input and output on opposing radial sides of the rotational axis A of the rotor 34. The pump inlet 13 receives fluid or inputs lubricant to be pumped (typically oil in the automotive context) from a source 52 (see FIG. 10) and into the housing 12. The pump outlet 15 is used for discharging or delivering the pressurized fluid or lubricant to the system 25, e.g., transmission or engine. (The terms “fluid” and “lubricant” are used interchangeably throughout this disclosure and not intended to limit this disclosure in any way.)

As known in the art, the pump has at least one intake or inlet port 28 (e.g., see FIG. 7A, which shows two ports 28) for intaking fluid (lubricant) to be pumped (e.g., from inlet 13 of housing 12). The inlet 13 is used for delivering or communicating fluid into a pressure chamber 55. Port(s) 28 communicate this fluid to the pressure cam 20 or ring. The pump also has at least one outlet port 30 (e.g., see FIGS. 4 and 7B) for discharging the fluid from the pump (e.g., and then out of housing 12 via outlet 15). The inlet port(s) 28 and outlet port(s) 30 may be diametrically opposed to each other with regards to the rotational axis A. The inlet port(s) 28 and outlet port(s) 30 each may have a substantially polygonal or a substantially crescent shape, for example, within the pump and may be formed through the same wall located on one axial side or both axial sides of the housing (with regard to the rotational axis A of the rotor 34). Further, pockets 30A and/or pockets 30B may be provided in the pump to assist in fluid / lubricant delivery and discharge. Such features are also described and referenced later with regards to FIGS. 7A-7C. Generally, these structures are conventional, and need not be described in detail. The shape of the pump inlet and/or pump outlet is not intended to be limiting. Other configurations may be used, such as differently shaped or numbered ports, etc. Further, it should be understood that more than one inlet or outlet may be provided (e.g., via multiple ports).

FIGS. 3 and 4 illustrate parts of the exemplary vane pump 10 of FIG. 1 in greater detail. A first plate 22 and a second plate 24 define a pressure chamber of the pump 10. More specifically, the first plate 22 and second plate 24 are disposed at opposite sides of the pressure chamber (such that chamber(s) are disposed axially therebetween) and in contact therewith. The first plate 22 includes a central opening 19B, through which the drive shaft 18 may optionally extend. The first plate 22 includes a flange or lip 23 that may be used for fastening the pump to an adjacent vehicle component (e.g., transmission case 12, as shown in FIG. 1). Thus, the shaft 18 may rotate along axis A (see FIG. 3) within the central opening 19B of the first plate 22.

The drive shaft 18 is configured to be driven by a driver (not shown) such that it rotates about axis A to drive the vane pump 10. Such a driver may include a drive pulley, drive shaft, engine crank, gear, or electric motor, for example. One or more support bearings may support the drive shaft 18. As seen in FIG. 4, for example, the drive shaft 18 extends through the first plate 22, and into an internal receiving space 31 (shown in FIG. 6A) of the chamber cam 20 (or cam ring). The drive shaft 18 may also connect to or extend at least partially into a portion of the second plate 24. In one embodiment, the drive shaft 18 is configured to extend through a central opening 19A of the second plate 24 along axis A.

The pressure chamber cam ring 20 is designed to be received or contained in the chamber 55 of the pump housing 12 such that it is in fitted relationship therewith. Pins 32 (see FIGS. 6A and 6B) may be inserted into or through openings, holes, or slots, generally noted as 51 in the Figures, in surrounding wall(s) of the cam ring 20 to connect with the first and second plates 22, 24. For example, one end of the pins 32 may be provided in receiving openings 32A (shown in FIG. 7A) or slots in (an inner surface of) the first plate 22 while the opposite end of the pins 32 is provided in openings or slots 32B in (an inner surface of) the second plate 24. Pins 32 secure the cam ring 20 relative to the plates 22, 24 and limit (e.g., rotational or sliding) movement of the cam. The chamber cam ring 20 has passageways 21 (see also FIG. 5) for intaking or delivery of lubricant from the inlet of the pump 10. The passageways 21 may be positioned approximately 180 degrees from each other (e.g., diametrically opposed), on either side of the drive shaft 18. The passageways 21 may be formed via cut-out portions in the cam ring 20, for example. The internal receiving space 31 of the pressure chamber cam ring 20 is defined by an inner wall having an inner surface 33. With the flanking of the plates 22, 24 on either side of the ring 20, the internal receiving space 31 defines at least one main pressure chamber for the fluid/lubricant (or oil). Further, the space 31 defines a rotor receiving space for receiving rotor 34 therein. The space 31 may have a generally oblong configuration (see FIG. 6B) or ovular configuration such that the rotor 34 may be disposed within the main pressure chamber while still providing at least one pressure chamber. (As described below, in the illustrated embodiment, there may be two pressure chambers 35, 37 provided in space 31, with the use of the rotor 34 therein.) This space 31 or volume in the pressure chamber communicates with the pump inlet and outlet via the inlet and outlet (or discharge) ports for drawing in oil, lubricant, or another fluid under negative intake pressure (suction) through the pump inlet, and expelling the same under positive discharge pressure (pressurized) out the pump outlet. In one embodiment, the outer wall(s) of the cam ring 20 may have a substantially similar shape as the receiving space 31. In another embodiment, the outer wall(s) of ring 20 may be one shape, e.g., circular, while the space 31 is another, e.g., oblong or ovular. In an embodiment, the cam ring 20 may include one or more relief portions 47 or cut-outs in its body or wall(s) at the discharge end thereof, such as illustrated in FIGS. 6A-6B. These portions 47 may be provided relative to the discharge end of the pressure chambers 35, 37 (i.e., near plate 24), and are generally understood to one of skill in the art and thus not further described here.

The rotor 34 is positioned within the main pressure chamber or, more specifically, in space 31 of the cam ring 20 such that a clearance is formed between the rotor 34 and inner cam surface 33. The rotor 34 (and its vanes 42, 44) may divide the internal receiving space 31 or pressure chamber into a first chamber 35 and a second chamber 37 as shown in FIGS. 6A and 6B. The first chamber 35 is formed on one side of the rotor 34 and the second chamber 37 is formed on another side and separated from the first chamber 35 by the rotor 34 (and vanes 42, 44). Each of the first and second chambers are defined as a volume between the rotor 34 and the inner cam surface 33 of the chamber which includes at least one intake port 28 and at least one discharge or outlet port 30 in communication therewith. Each of the first chamber 35 and second chamber 37 are in fluid communication with at least one of passageways 21 (see FIGS. 6A and 6B) of the cam ring 20 and one of the inlet and discharge ports. Accordingly, each of the inlet port(s) 28 is configured to be in fluid communication with one of the chambers 35 or 37 of pressure chamber 55 to deliver lubricant thereto (see also FIG. 6B). The first plate 22 and the second plate 24 further provide upper and lower boundaries of the first chamber 35 and second chamber 37.

The rotor 34 (or impeller) is rotatably mounted in the housing 12 within the internal receiving space 31 of the pressure chamber cam ring 20. The rotor 34 is configured for rotation within and relative to the cam ring 20. The rotor 34 is positioned along a central axis (axis A) that in the illustrated type of pump is typically coaxial with a central axis of the chamber (and/or space 31). In other types of pumps, these axes may be eccentric. As represented in FIG. 2, the rotor 34 is connected to the drive shaft 18 for rotation therewith. The rotor 34 includes an opening or center slot 36 configured to receive the shaft 18. The drive shaft 18 may have one or more or a series of splines 39 (see FIGS. 2 and 4) and grooves (not shown) around its outer circumference for cooperative engagement with corresponding grooves 38A and splines 38B (shown in FIGS. 6A and 6B, for example) provided in the center slot 36 of the rotor 34, to drivingly couple the rotor 34 to the shaft 18. For example, male splines 39 and female grooves of the drive shaft 18 may engage with a set of female grooves 38A and male splines 38B, respectively, which are disposed on an inner surface of the slot 36, in order to drivingly couple the rotor 34 to the drive shaft 18 for rotation about the axis A together. Of course, it should be understood that this illustrated design of the drive shaft and rotor is exemplary only, and not intended to be limiting. Other designs and/or devices may be used to drivingly couple the shaft 18 and rotor 34 together.

The rotor has a number of radial slots 40 and multiple vanes 42 and at least one less restricted vane 44 (described in detail later) that are received and movable within the radial slots 40. The vanes 42 and 44 are configured for radial movement, e.g., movement radially towards the inside surface 33 of the cam ring 20, away from an end of the slot that is closest to axis A. Centrifugal force may force the vane(s) 42, 44 radially outwardly at the initial stage or startup of the pump to engage and/or maintain engagement of distal end(s) of the vane(s) 42, 44 with the inside or inner surface 33 of the cam ring 20 during rotation of the rotor 34. Pressurized fluid further forces the vanes outwardly and in engagement with the chamber cam 20. The vanes 42, 44 extend across the clearance of the chambers 35, 37 and are movable with respect to their slots 40 to accommodate variances in the clearance. Thus, the vane(s) 42, 44 can be sealingly engaged with the inner surface 33 of the cam ring 20 such that rotating the rotor 34 draws fluid in through the pump inlet by negative intake pressure and outputs the fluid out through the outlet by positive discharge pressure. Generally, this type of mounting and functionality of the pump is conventional and well known, and need not be detailed further.

As the vanes 42, 44 are moved radially outwardly and in contact with the inner surface 33 of the cam ring 20, the chambers 35, 37 are divided into compartments that receive lubricant.

During operation, the drive shaft 18 rotates the rotor 34 so that the vanes 42, 44 are rotated within the cam ring 20. The housing 12 and inlet 13 draw the lubricant into the chamber 55 through inlets 28 and the passageways 21 and then into compartments of each of the chambers 35, 37, for pressurization. As the rotor 34 continues rotating, the vanes 42, 44 move the pressurized lubricant to a distal side or end of the corresponding chamber (e.g., a side that is approximately 90 degrees relative to passageway 21) to discharge pressurized lubricant from the pressure chamber via a corresponding discharge port(s). Additionally, as described later below, while the rotor 34 rotates and lubricant enters the pump 10 via its inlet and exits via its outlets, centrifugal force and hydraulic pressure up through back pressure ports 50 may push the vanes 42, 44 radially towards the inner surface 33 of the pressure chamber 20 (and thus towards the walls of the cam 20 (and the housing 12)). The lubricant exits through the discharge ports and outlet(s) of the pump (described below), to and through outlet 15.

FIG. 7A illustrates an inner face, underside, or inner side (i.e., the side that faces chamber 20) of the first plate 22 in accordance with an embodiment. The first plate 22 is a cover plate, for example, and helps define the pressure chamber(s) 35, 37 within the pump 10. The first plate 22 may be secured to the second plate 24. The first plate 22 includes central opening 19B for receipt of at least a portion of the drive shaft 18, thus centering the first plate 22 on axis A. Optionally, the drive shaft 18 may extend through the opening 19B. The inner face of the first plate 22 faces the chamber and thus the pressure chambers, rotor 34, and vanes 42, 44. The first plate 22 may be rotationally fixed to the chamber via flanges (not shown) or O-rings, for example.

The first plate 22 also includes inner depressions 48A (or inner portings), inlet ports 28, and pockets 30A (which may also be referred to as ports) on its inner face or underside. When the pump is assembled and operating, the pockets 30A of the pump intake or receive lubricant from the chamber(s) 35, 37 to fluidly communicate with and deliver output pressurized lubricant through the outlets 30, and thus may also be referred to as discharge ports or “discharge pockets” 30A. The inlet ports 28 and discharge pockets 30A may be recesses formed in the first plate 22, with the inlet ports 28 being diametrically opposed to each other (with regards to axis A). The pockets 30A may also be diametrically opposed to each other (with reference to axis A). The pockets 30A may be formed between or about or at 180 degrees relative to each other and about 90 degrees relative to the inlet ports 28, as shown in FIG. 7A. The discharge pockets 30A and outlet ports 30 are fluidly connected (e.g., see FIG. 4) and configured to discharge fluid or lubricant via outlet 15 (see FIG. 2) to outside the housing 12. The inner depressions 48A of first plate 22 are also recessed portions that are provided adjacent to the central opening 19B and at least partially surround the opening 19B. Although two depressions 48A are shown in FIG. 7A, the number and shape of the depressions 48A is not intended to be limited. In an embodiment, each inner depression 48A has an arcuate shape. In one embodiment, the inner depressions 48A substantially surround the central opening 19B. The depressions 48A may be positioned or spaced circumferentially around the central opening 19B, for example. Fluid pressure build-up in these inner depressions 48A—as a result of receiving fluid from back pressure ports 50—causes action (i.e., fluid pressure) on the vanes 42, 44 to thereby deliver pressurized fluid to the rotor slots to push the vanes outwardly (away from the central axis A) and keep the vanes 42, 44 in contact with the inner surface 33 of the pressure chamber cam ring 20. The first plate 22 also includes receiving openings or cut-outs for receipt of first ends of pins 32.

FIG. 7B illustrates an inner face or inner side (i.e., the side that faces the pressure chambers) of the second plate 24 in accordance with an embodiment. FIG. 7C illustrates an outer or bottom side (the opposite side) of the second plate 24 of FIG. 7B. The second plate 24 is a pressure plate that defines the pressure chamber(s) 35, 37 within the pump 10. During operation, pressure is applied on an outer surface (bottom) of the second plate 24, due to fluid pressure build up, to compress the second plate 24 towards and together with the pressure chamber and to minimize leakage paths (further described below). The second plate 24 can also be bolted or secured to the first plate 22 (e.g., via pins 32 at in walls of the chamber), and may include receiving openings or cut-outs for receipt of second ends of pins 32. As previously noted, in one embodiment, the second plate 24 includes central opening 19A for receipt of at least a portion of the drive shaft 18, thus centering the second plate 24 on axis A. Optionally, the drive shaft 18 may extend through the opening 19A. The inner face of the second plate 24 faces the main chamber 55 and thus the pressure chambers 35, 37, rotor 34, and vanes 42, 44. The second plate 24 may be rotationally fixed to the chamber 55 via flanges (not shown) or O-rings, for example.

The second plate 24 also includes inner depressions 48B (or inner portings), back pressure ports 50, outlet ports 30, and ports or pockets 30B (also referred to as delivery ports or delivery pockets) on its inner face or inner side. When the pump is assembled and operating, the pockets 30B of the pump receive lubricant from the inlet 13 to fluidly communicate with and deliver lubricant into the pressure chamber (or chambers 35, 37), and thus may also be referred to as inlet ports or pockets 30B. The pockets 30B may be recesses formed in the second plate 24 that are diametrically opposed to each other (with reference to axis A). The outlet ports 30 are openings or holes that extend through the thickness of the second plate 24 (see bottom view in FIG. 7B and FIG. 4) and are used to output lubricant from the chamber(s) towards the outlet 15. In an embodiment, the outlet ports 30 allow fluid to flow from the first chamber 35 and/or second chamber 37 to a single outlet path of the pump. The outlet ports 30 may also be diametrically opposed to each other (with reference to axis A). The pockets 30B may be formed between or at or about 180 degrees relative to each other and about 90 degrees relative to the outlet ports 30, as shown in FIG. 7B. The inner depressions 48B are also recessed portions that are provided adjacent to the central opening 19A and at least partially surround the opening 19A. Although two depressions 48B are shown in FIG. 7B, the number and shape of the depressions 48A is not intended to be limited. In an embodiment, each inner depression 48B has an arcuate shape. The back pressure ports 50 are provided between the inner depressions 48B, also around and partially surrounding the central opening 19A. Although two ports 50 are shown in FIG. 7B, the number and shape of the back pressure ports 50 is not intended to be limited. The back pressure ports 50 are openings or holes that extend through the thickness of the second plate 24. In one embodiment, the inner depressions 48B and back pressure ports substantially surround the central opening 19A. The depressions 48B and ports 50 may be positioned or spaced circumferentially around the central opening 19A, for example. The back pressure ports 50 may be referred to as vane pressurizing ports. When pressurized fluid builds up under or below the second plate 24 (e.g., in a lower portion of housing 12), the pressurized fluid may be received through the back pressure ports 50 to pressurize the vanes (previously noted above). Pressurized fluid may be directed from ports 50 and partially contained in the inner depressions 48B. Fluid pressure build-up in these inner depressions 48B causes action (i.e., pressure) on the vanes 42, 44 to thereby deliver pressurized fluid to the rotor slots to push the vanes outwardly (away from the central axis A) and keep the vanes 42, 44 in contact with the inner surface 33 of the pressure chamber cam ring 20. Generally, such features are known and thus are not further described herein.

In addition to the above described features, which are generally understood by those of ordinary skill in the art, the rotor 34 of the disclosed pump assembly 10 includes at least one less restricted vane 44 therein, in addition to the remaining/other vanes 42. The less restricted vane(s) 44 is designed to move within its slot 40 before the other vanes 42. In accordance with one embodiment, for example, a distance (D) between an outer face of the at least one vane 44 and an inner face of its respective slot is greater than distances/standard clearances between the remaining vanes and inner sides of their respective slots, to facilitate radially outward movement of the vane 44 towards the inside surface 33 of the pressure chamber by centrifugal force during initial start-up of the pump, before the radial outward movement of vanes 42 towards inside surface 33. FIGS. 8A and 8B illustrate exemplary details of one embodiment of employing a less restricted vane 44 that has a different thickness relative to thicknesses of the other vanes 42, thus providing a greater distance D (see FIG. 9 for example of location of D) between vane 44 and the inside surface of its slot 40, while the remaining vanes 42 have a standard clearance C. That is, the less restricted vane 44 has a lower thickness than the remaining vanes 42. For illustrative purposes only, the distance D and clearance C are shown as being on either side of the vanes 44 and 42 (respectively) in the Figure. However, it should be understood that the distance or clearance on either side of the vanes 44, 42 may vary slightly, e.g., as the vanes move therein.

In an embodiment, each of the slots 40 have an essentially similar width W_(S), height, and length L_(S) (see FIG. 8A). Each of the vanes 42 and 44 provided in the rotor 34 have a radial length L (defined as a measurement between a proximal end of the vane that is near the axis A and an opposite end near the inner surface 33) and height H (defined as a measurement between a bottom end of the vane adjacent to the second plate 24 and a top end of the vane adjacent to the first plate 22). In one embodiment, each of the vanes 42, 44 has substantially similar radial length L. In another embodiment, each of the vanes has a substantially similar height H. In yet another embodiment, each of the vanes 42, 44 have both substantially similar length L and height H.

Each of the vanes 42 and 44 also has a thickness, also referred to herein as a width (defined as a measurement between each major side of the vane that is positioned between walls of the slot 40). For example, in accordance with an embodiment, each of the vanes 42 has a thickness W1, and less restricted vane 44 has a thickness W2, as shown in FIG. 8. In accordance with one embodiment, W2<W1, such that less restricted vane 44 (W2) is thinner or of a reduced thickness/width as compared to the thickness or widths (W1) of vanes 42. For example, the difference in widths (W1−W2) may be between approximately 0.020 to approximately 0.100 millimeters (mm), both inclusive, in accordance with an embodiment. In one embodiment, the difference in widths (W1−W2) may be between approximately 0.020 to approximately 0.050 millimeters (mm), both inclusive. In another embodiment, the lower thickness W2 of vane 44 is approximately less than or equal to approximately 0.100 mm thinner than the thicknesses of the remaining vanes 42. Accordingly, this reduced thickness allows the less restricted vane 44 to displace within its respective slot 40 radially towards the inside surface 33 of the cam ring 20 before the other vanes 42 move within their slots 40 (such as during cold start). In such a case, i.e., where vanes 42 and less restricted vane 44 have different widths, the dimensions (e.g., W_(S), height, and length L_(S)) of the slots receiving the vanes 42, 44 therein may remain the same.

In accordance with an embodiment, the width (or thickness) of the less restricted vane(s) 44 is less than or equal to approximately 0.100 mm thinner than the width (or thickness) of the other vanes 42. In accordance with another embodiment, the width (or thickness) of the less restricted vane(s) 44 is less than or equal to approximately 0.050 mm thinner than the width (or thickness) of the other vanes 42. In yet another embodiment, the width (or thickness) of the less restricted vane(s) 44 is approximately 0.020 mm thinner than the width (or thickness) of the other vanes 42. The width of the vane(s) 44 is not equal to the width of vanes 42. It should be understood by one of ordinary skill in the art that the difference in thickness or width of the at least one less restricted vane 44 (or a slot 41, as described in an embodiment later) is designed such that the moving distance of the less restricted vane 44 (or D*2 in slot 41) in its respective slot is greater than mere inconsequential differences that may be caused due to manufacturing tolerances. Generally, the manufacturing tolerance range may also be, for example, approximately 0.020-0.060 mm.

Using the example ranges above, in one embodiment, the width W1 of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive), and the width W2 of the at least one less restricted vane 44 may be approximately 0.90 mm to approximately 1.98 mm (inclusive), while still providing a difference between approximately 0.020 to approximately 0.100 millimeters (mm) as compared to W1. In another embodiment, the width W1 of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive), and the width W2 of the at least one less restricted vane 44 may be approximately 0.95 mm to approximately 1.98 mm (inclusive), while still providing a difference between approximately 0.020 to approximately 0.050 millimeters (mm) as compared to W1. In yet another embodiment, the width W1 of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive), while the width W2 of the at least one less restricted vane 44 may be approximately 0.9 mm to approximately 1.9 mm (inclusive). In still yet another embodiment, the width W1 of the vanes 42 may be approximately 1.0 mm, while the width W2 of the at least one less restricted vane 44 may be approximately 0.9 mm.

The method for forming the less restricted/loose/narrower vane as described with reference to FIG. 8 above is not intended to be limited. Such a less restricted vane (like vane 44) may be formed (e.g., molded or cast) to a different thickness or width, in accordance with one embodiment. In another embodiment, an existing vane (like vane 42) may be altered or machined by a machining process or tool, for example, i.e., carving or shaving off a desired thickness to reduce its width.

In accordance with another embodiment, at least two less restricted vanes 44 of a different thickness or width W2 are provided in the rotor 34, while the remaining vanes 42 in the rotor 34 have similar thickness W1. In yet another embodiment, less than half of the vanes in the rotor 34 are less restricted vanes 44 that have a different thickness or width W2 relative to widths W1 of the remaining vanes 42. In an embodiment, the less than half of the less restricted vanes 44 have the same thickness.

FIG. 9 illustrates another embodiment of employing a less restricted vane in the pump assembly 10, wherein at least one radial slot (referred to as slot 41) of the slots 40 in the rotor 34 has a different width relative to widths of the other slots. Each of the vanes 42 provided in the slots 40 and 41 has similar or the same width, i.e., vane width W. The width of slot 41 may be altered by a machining process or tool, for example. In some cases, existing or prefabricated rotors may be used to form such a radial slot 41. In this illustrative embodiment, it is the width of the slot 41 that changes the distance D relating to the slot for the less restricted vane as compared to the standard clearance C or width of slots 40 for vanes 42, while the other dimensions remain substantially the same. For example, each of the slots 40 and 41 provided in the rotor 34 have a radial length (like L as shown in FIG. 8A) (defined as a measurement between an end of the opening within the rotor 34 that is near the axis A and an opposite end at an outer surface of the rotor 34) and height (like H as shown in FIG. 8A) (defined as a measurement between a top end of the opening at the top surface of the rotor 34 and a bottom end of opening at the bottom surface of the rotor 34). In one embodiment, each of the slots 40, 41 has substantially similar radial length. In another embodiment, each of the slots has a substantially similar height. In yet another embodiment, each of the slots 40, 41 have both substantially similar length and height.

Each of the slots 40 has a width W_(S). The width of a slot in the rotor 34 may be defined as a measurement between the walls defining the slot opening, that are configured to receive a vane therebetween or therein. Width W_(S) may be defined as W+C or, as shown in FIG. 9, W+C*2. In accordance with an embodiment, slot 41 may have a width W_(S1) that is different than the widths W_(S) of the slots 40. Width W_(S1) may be defined as W+D or, as shown in FIG. 9, W+D*2. In accordance with one embodiment, W_(S1)>W_(S), such that the slot 41 is wider than the other slots 40. That is, as shown in FIG. 9, W_(S) and W_(S1) are not equal and W_(S) is less than W_(S1). Accordingly, the vane 42 positioned within the slot 41 as shown in FIG. 9 may be referred to as a less restricted vane or loose vane, because such a vane received within the slot 41 is configured for radial displacement towards the inside surface 33 of the cam ring 20 before radial movement of the other vanes 42 within the other slots 40, since the associated slot 41 itself is larger (in width). This is because the distance D between an outer face of the at least one vane 42 contained in the slot 41 and an inner face of its respective slot is greater than a distance designed for a standard clearance C for each [remaining] vane 42. (Thus, clearance C is less than distance D.)

Of course, it should again be noted and understood that the clearance C on either side of vane 42 and distance D on either side of the less restricted vane as depicted in FIG. 9 are not intended to be limited with regards to the referenced spacing being equal or consistent, such that the vane 42 and/or less restricted vane is continually equidistant relative to the inner side of its respective slot. Rather, one of ordinary skill in the art will understand the fluid nature of the vanes within their slots (e.g., in the lateral direction, or towards and away from the inner sides or walls of its slot) based on the receipt of fluid in the chamber(s).

For example, in one embodiment, the difference in widths (W_(S1)−W_(S)) may be between approximately 0.020 to approximately 0.100 millimeters (mm), both inclusive, in accordance with an embodiment (i.e., width W_(S1) of slot 41 is between approximately 0.02 mm and approximately 0.100 mm higher than the widths of the other slots 40 of width W_(S)). In one embodiment, the difference in widths (W_(S1)−W_(S)) may be between approximately 0.020 to approximately 0.050 millimeters (mm), both inclusive. In another embodiment, the width W_(S) of slot 40 in FIG. 9 is approximately less than or equal to approximately 0.100 mm thinner than the width W_(S1) of the at least one slot 41. Accordingly, this larger width W_(S1) of slot 41 allows the less restricted vane 42 therein to displace within slot 41 towards the inside surface 33 of the cam ring 20 before the other vanes 42 in slots 40 move within their respective slots 40 (such as during cold start). In such a case, each of the vanes 42 provided in rotor 34 of the illustrated embodiment of FIG. 9 have a substantially similar thickness W, height (H), and length (L).

In accordance with an embodiment, the width W_(S1) of the slot(s) 41 is at least approximately 0.020 mm greater in width as compared to width W_(S.) of the other slots 40. In accordance with another embodiment, the width W_(S1) of the slot(s) 41 is at least approximately 0.050 mm greater in width as compared to width W_(S.) of the other slots 40. In yet another embodiment, the width W_(S1) of the slot(s) 41 is at least approximately 0.100 mm greater in width as compared to width W_(S.) of the other slots 40. In an embodiment, the width W_(S1) of the slot(s) 41 is not more than approximately 0.25 mm greater in width as compared to width W of the vanes 42. In another embodiment, the width W_(S1) of the slot(s) 41 is not more than approximately 0.15 mm greater in width as compared to width W of the vanes 42. It should be understood by one of ordinary skill in the art that the difference in width of the at least one slot 41 is designed such that the total distance D*2 of the slot 41 is greater than mere inconsequential differences that may be caused due to manufacturing tolerances. Generally, the manufacturing tolerance range may also be, for example, approximately 0.020-0.060 mm.

In an embodiment, the distance D for the less restricted vane in slot 41 may be between approximately 0.050 mm and approximately 0.100 mm per side (inclusive), while the spacing or normal clearance C between the outside surface of each vane 42 and its slot surface (in slot 40) may be between approximately 0.010 mm and approximately 0.025 mm per side (inclusive). In one embodiment, the width W of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive). Thus, based on the examples above for C and D, then, in accordance with one embodiment, a width W_(S1) of slot 41 may be between W+approximately 0.1 mm and W+approximately 0.2 mm (inclusive) (i.e., W+D*2), and a width of slot(s) 40 may be between W+approximately 0.02 mm and W+approximately 0.05 mm (inclusive) (i.e., W+C*2).

In another embodiment, the distance D for the less restricted vane in slot 41 may be between approximately 0.0175 mm and approximately 0.100 mm per side (inclusive), while the spacing or normal clearance C between the outside surface of each vane 42 and its slot surface (in slot 40) may be between approximately 0.005 mm and approximately 0.05 mm per side (inclusive).

In yet another embodiment, the total distance (D*2) between the outside surfaces of the less restricted vane and surfaces in slot 41 may be between approximately 0.050 mm and approximately 0.100 mm (inclusive), while the total spacing or normal clearance (C*2) between the outside surfaces of each vane 42 and its slot surface (in slot 40) may be between approximately 0.010 mm and approximately 0.025 mm per side (inclusive).

In an embodiment, the total clearance (C*2) for the vanes in the slots 40 may be between approximately 15 micron and approximately 100 micron (inclusive). Thus, if the width W of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive), the widths W_(S) of the slots 40 may be between approximately 1.015 mm and approximately 2.1 mm (inclusive), in accordance with an embodiment. Further, in such an embodiment, the width W_(S1) of the at least one slot 41 may be approximately 35 micron and approximately 200 micron (inclusive) larger than the width W_(S), i.e., width(s) W_(S1) of the slot(s) 41 may be between approximately 1.035 mm and approximately 2.2 mm (inclusive).

In another embodiment, the distances D for the vanes in the slot 41may be between approximately 20 micron and approximately 100 micron (inclusive) larger than total clearance (C*2), i.e., total distance (D*2) on either side of vane 41 is approximately 40 micron to approximately 200 micron. That is, in an embodiment wherein the width W of the vanes 42 may be approximately 1.0 mm to approximately 2.0 mm (inclusive), the width W_(S1) of the at least one slot 41 may be between approximately 1.040 mm and approximately 2.2 mm (inclusive), while the widths W_(S) of the slots 40 may be between approximately 1.015 mm and approximately 2.1 mm (inclusive), wherein the widths W_(S) of the slots 40 are at least 10 micron smaller than the width W_(S1) of the slot(s) 41.

In yet another embodiment, a width W_(S1) of slot 41 may be between W+approximately 0.017 mm and W+approximately 0.2 mm (inclusive) (W+D*2), and a width W_(S) of slot(s) 40 may be between W+approximately 0.015 mm and W+approximately 0.1 mm (inclusive) (W+C*2), wherein W_(S) and W_(S1) are not equal and W_(S) is less than W_(S1).

In yet another embodiment, a width W_(S1) of slot 41 may be between W+approximately 0.035 mm and W+approximately 0.2 mm (inclusive) (W+D*2), and a width W_(S) of slot(s) 40 may be between W+approximately 0.015 mm and W+approximately 0.1 mm (inclusive) (W+C*2), wherein W_(S) and W_(S1) are not equal and W_(S) is less than W_(S1).

In still yet another embodiment, a width W_(S1) of slot 41 may be between W+approximately 0.05 mm (50 micron) and W+approximately 0.1 mm (100 micron) (inclusive) (W+D*2), and a width W_(S) of slot(s) 40 may be between W+approximately 0.02 mm and W+approximately 0.9 mm (inclusive) (W+C*2), wherein W_(S) and W_(S1) are not equal and W_(S) is less than W_(S1).

In yet another embodiment, the width W_(S1) of the at least one slot 41 may be between approximately 0.02 mm and approximately 0.100 mm higher than the width W_(S) of the other remaining slots 40.

Further in accordance with an embodiment, the widths W_(S) of the slots 40 are between approximately 10 micron to approximately 200 micron smaller than the width W_(S1) of the slot(s) 41.

In an embodiment, each of the vanes 42 provided in rotor 34 of the illustrated embodiment of FIG. 9 may have a substantially similar thickness W, height (H), and length (L), with W_(S1)>W_(S).

In accordance with another embodiment, at least two slots 41 of a different width are provided in the rotor 34, while the remaining slots 40 in the rotor 34 have similar width. In yet another embodiment, less than half of the slots 41 in the rotor 34 are of a different width (providing less than half of vanes that are less restricted vanes) as compared to the widths of the other slots 40. In an embodiment, these less than half of slots 41 have the same width.

Although not explicitly detailed above, each of the exemplary embodiments and ranges noted with respect to the widths W_(S1), W_(S) of the slot(s) 41, 40 noted above could also be similarly applied with regards to the thicknesses/widths W1, W2 of the vanes 42, 44 described with respect to FIG. 8.

As previously mentioned, use of at least one less restricted vane in a rotor 34 in a pump assembly 10 as herein disclosed and described facilitates cold start of the pump in highly viscous oil by allowing easier radial displacement of the vane by centrifugal force for initially moving oil and pressurizing the fluid, and thus earlier initial build-up of pressure within the outlet of the pump, and hence in the inner porting or depressions. The use of a less restricted vane reduces the required amount of oil shear (breakdown of its viscosity) at colder temperatures, thereby faster delivery of the oil/fluid to the pressure chamber(s). The pressure in the inner porting/depressions thereafter acts on the vanes to keep the vanes in constant contact with the inner face of the pressure chamber(s).

Additional parts may also be provided along with pump 10 and/or its housing 12. For example, as previously noted with reference to FIG. 1, the pump assembly 10 may include a number of O-rings for sealing engagement within the housing 12 or another vehicle part. The pump 10, its housing 12, and/or parts thereof (e.g., first and second plates 22, 24) may include grooves (not shown) along an inner or outer periphery thereof for receipt and installation of the O-rings.

FIG. 10 is a schematic diagram of a system 25 in accordance with an embodiment of the present disclosure. The system 25 can be a vehicle or part of a vehicle, for example. The system 25 includes a mechanical system such as an engine 56 (e.g., internal combustion engine) and/or a transmission (e.g., represented with case 12 in FIG. 1) of an automotive vehicle for receiving pressurized lubricant from the pump 10. The pump 10 receives (input via pump inlet) lubricant (e.g., oil) from a lubricant source 52 and pressurizes and delivers it to the engine 56 (output via outlet). A sump or tank 58 may be the lubricant source 52 that inlets to the pump 10. A controller 54 may be designed for implementing actuation of the system 25 and/or pump 10.

While the principles of the disclosure have been made clear in the illustrative embodiments set forth above, it will be apparent to those skilled in the art that various modifications may be made to the structure, arrangement, proportion, elements, materials, and components used in the practice of the disclosure.

It will thus be seen that the features of this disclosure have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this disclosure and are subject to change without departure from such principles. Therefore, this disclosure includes all modifications encompassed within the spirit and scope of the following claims. 

What is claimed is:
 1. A vane pump comprising: an inlet for receiving fluid from a source; an outlet for delivering pressurized fluid to a system therefrom; a pressure chamber cam having an internal space defined by an inside surface and communicated to the inlet and outlet; a rotor rotatably received within the internal space of the pressure chamber cam, the rotor having a plurality of radial slots and a plurality of vanes received and movable within respective radial slots radially towards the inside surface of the pressure chamber cam; and a drive shaft connected to the rotor for rotating the rotor to cause the vanes to draw lubricant in from the inlet and pressurize the lubricant for expelling out through the outlet; the rotor having the radial slots thereof communicated to the pressurized fluid to bias the vanes radially outward therefrom using the fluid pressure; wherein, for at least one of the plurality of vanes, a distance between an outer face of the at least one vane and an inner face of its respective slot is greater than distances between outer faces of the remaining vanes and inner faces of their respective slots to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 2. The vane pump according to claim 1, wherein at least one of the plurality of vanes in the rotor has a lower thickness relative to thicknesses of the remaining vanes to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 3. The vane pump according to claim 1, wherein at least one of the plurality of radial slots in the rotor has a higher width relative to widths of other slots, such that the respective vane received within the at least one radial slot of different width is configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 4. The vane pump according to claim 2, wherein each of the plurality of vanes has essentially the same radial length.
 5. The vane pump according to claim 2, wherein each of the plurality of vanes has essentially the same height.
 6. The vane pump according to claim 2, wherein at least two of the plurality of vanes in the rotor have the lower thickness relative to the thicknesses of the remaining vanes to facilitate radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during the initial start-up of the pump.
 7. The vane pump according to claim 6, wherein the at least two vanes have the same thickness.
 8. The vane pump according to claim 2, wherein less than half of the plurality of vanes in the rotor have the lower thickness relative to the thicknesses of the remaining vanes, and wherein the less than half of the plurality of vanes have the same thickness.
 9. The vane pump according to claim 3, wherein each of the plurality of slots has essentially the same radial length.
 10. The vane pump according to claim 3, wherein each of the plurality of vanes has essentially the same thickness.
 11. The vane pump according to claim 3, wherein at least two of the plurality of slots in the rotor have the higher width relative to widths of the other slots, such that the at least two vanes are configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 12. The vane pump according to claim 11, wherein the at least two slots have essentially the same width.
 13. The vane pump according to claim 9, wherein less than half of the plurality of slots in the rotor have a different width relative to widths of the other slots, and wherein the less than half of the plurality of slots have the same width.
 14. The vane pump according to claim 1, further comprising a first plate and a second plate provided on either side of the pressure chamber cam, wherein the drive shaft extends through the first plate and into the internal space of the pressure chamber cam.
 15. The vane pump according to claim 14, wherein the drive shaft is further connected to the second plate.
 16. The vane pump according to claim 2, wherein the lower thickness of the at least one of the plurality of vanes is between approximately 0.02 mm and approximately 0.100 mm thinner than the thicknesses of the remaining vanes.
 17. The vane pump according to claim 3, wherein the higher width of the at least one radial slot is between approximately 0.02 mm and approximately 0.100 mm higher than the widths of the other slots.
 18. The vane pump according to claim 1, wherein the system is a transmission or an engine.
 19. A system comprising: an engine or a transmission, and a vane pump, the vane pump comprising: an inlet for receiving fluid from a source; an outlet for delivering pressurized fluid to the engine or transmission; a pressure chamber cam having an internal space defined by an inside surface and communicated to the inlet and outlet; a rotor rotatably received within the internal space of the pressure chamber cam, the rotor having a plurality of radial slots and a plurality of vanes received and movable within respective radial slots radially towards the inside surface of the pressure chamber cam; and a drive shaft connected to the rotor for rotating the rotor to cause the vanes to draw lubricant in from the inlet and pressurize the lubricant for expelling out through the outlet; the rotor having the radial slots thereof communicated to the pressurized fluid to bias the vanes radially outward therefrom using the fluid pressure; wherein, for at least one of the plurality of vanes, a distance between an outer face of the at least one vane and an inner face of its respective slot is greater than distances between outer faces of the remaining vanes and inner faces of their respective slots to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 20. The system according to claim 19, wherein at least one of the plurality of vanes in the rotor has a lower thickness relative to thicknesses of the remaining vanes to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.
 21. The system according to claim 19, wherein at least one of the plurality of radial slots in the rotor has a higher width relative to widths of other slots, such that the respective vane received within the at least one radial slot of different width is configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 